Kent and South London water situation: November 2024 summary
Updated 13 December 2024
Applies to England
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1. Summary
The whole of the Kent and South London (KSL) area received 87% of the long term average (LTA) rainfall during November. Rainfall received across all catchments was normal for this time of year. At the end of November, soil moisture deficits (SMDs) were 1mm or less in most catchments, except for 3 catchments in the northeast of KSL. Monthly mean flows (MMFs) ranged from normal to notably high in November. Groundwater levels in the Chalk at most locations across the KSL area continued to slowly fall or have now stabilised. The Lower Greensand aquifer at Riverhead continued to register groundwater levels that are notably high for this of the year. Levels at the end of the month at the 5 water company reservoirs in the area ranged from normal to exceptionally high. Levels increased in most KSL reservoirs in November.
2. Rainfall
The whole of the KSL area received 87% of the LTA rainfall during November. Rainfall received across all catchments was normal for this time of year. The percentage of LTA rainfall received across catchments ranged from 119% across Lower Wey rainfall area to 70% in the Thanet Chalk rainfall area. The highest daily rainfall total of 37mm for November was recorded at Westerham PS rain gauge in the Darent catchment on 26 November. The next highest daily rainfall totals were on 23, 18, 24 and 17 November and ranged from 20.8mm to 10.6mm. Only one dry day, where less than 0.2mm of rainfall was received, was registered at the beginning of the month.
3. Soil moisture deficit and recharge
At the end of November, SMDs were 1mm or less in most catchments, except for 3 catchments in the northeast of KSL:
- North West Grain recorded 41mm
- Sheppey recorded 47mm
- Thanet Chalk registered the highest SMDs this month at 86mm
SMDs decreased in most catchments in November due to the increase in the effective rainfall received. Across the whole area, on average, effective rainfall received this month was at 112% of the LTA. In November, the difference from LTA decreased in all catchments in the south and North Kent Chalk.
4. River flows
MMFs ranged from normal to notably high in November. Eight out of the 11 key flow sites saw normal MMFs. Two key flow sites located in the centre of the patch saw above normal MMFs, and one key flow site, located in the east of the area, saw notably high MMFs. Dour at Crabble recorded the highest MMF highest percentage LTA of 144% for the month of November. East Stour at South Willesborough recorded the lowest percentage LTA of 85%.
5. Groundwater levels
At the end of November, groundwater levels in the Chalk are predominantly above normal for this time of year. Levels at Wolverton in the east of the patch are now normal. The Lower Greensand aquifer at Riverhead continued to register groundwater levels that are notably high. Groundwater levels in the Chalk at most locations across the KSL area continued to slowly fall or have now stabilised. A slight rise was observed at the end of the month at Wolverton and at Chipstead, in the west. The slowdown or slight rise in groundwater levels is consistent with the effective rainfall of 112% of the LTA. It is also consistent with the depletion of SMDs seen in most areas by the end of November.
6. Reservoir stocks
Levels increased in most KSL reservoirs in November. Only Darwell reservoir had a marginal decrease in levels this month. At the end of November, reservoir levels were:
- normal at Darwell at 79% and Bewl at 64%
- above normal at Bough Beech at 92%
Weir Wood and Powdermill reservoirs were full at the end of this month. Weir Wood reservoir remained offline during November.
7. Environmental impact
Twenty fluvial flood alerts and three flood warnings were issued from 25 to 27 November.
Author: Groundwater and Hydrology Team, ksl.gwh@environment-agency.gov.uk
Contact Details: 03708 506 506
All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.